CN103977802B - Nanometer needle-like nickel bag graphite compound particle and its preparation method and application - Google Patents

Abstract

The present invention relates to the synthesis of nano-needle-shaped nickel-coated graphite composite particles for p-aminophenol and its preparation method and application. It is nano-needle-shaped nickel-coated flake graphite particles. After being stirred and reacted in the nickel plating solution, suction filtration, washing and drying are carried out to obtain nano needle-shaped nickel-coated graphite composite particles. Compared with the prior art, the present invention has the following main advantages: the activity of the catalyst prepared by the present invention is higher, for example: the reaction rate constant (k) used to catalyze the reduction of p-nitrophenol by NaBH4 is 8.61×10 ^-2 min ^{- 1.} The k value used to catalyze this reaction is larger than that of the graphene oxide/nickel nanocomposite prepared by Ji et al. (its rate constant is 14.82×10 ^-3 min ^-1 ); The graphite composite particle has magnetism and is convenient for recycling and reuse; the preparation technology of the invention is simple, the cost is low, and it is convenient for popularization and application.

Description

Nanoacicular nickel-coated graphite composite particles and its preparation method and application

technical field

The invention relates to the technical field of composite materials and catalysis, in particular to a nano needle-shaped nickel-coated graphite composite particle for synthesizing p-aminophenol and its preparation method and application.

Background technique

P-aminophenol (PAP) is an important medicine, dyestuff and organic synthesis intermediate, and it can also be used to manufacture various dyes, dyeing agents, rubber antioxidants, photographic developers, pesticide antioxidants and oil additives. At present, the synthesis methods of p-aminophenol mainly include p-nitrophenol iron powder reduction method, nitrobenzene method and p-nitrophenol catalytic hydrogenation method. Among them, the catalytic hydrogenation reduction method of p-nitrophenol has the advantages of simple operation, high product yield and good quality, so it is widely used. In the process of synthesizing p-aminophenol by the catalytic hydrogenation reduction method of p-nitrophenol, the role of the catalyst is very important, and its performance directly affects the quality of the reduction product. A catalyst with high activity and high selectivity can improve the yield of p-aminophenol. Increase production efficiency and reduce production costs.

At present, there are two types of catalysts: one type of catalyst is a noble metal type catalyst supported by Al ₂ O ₃ , TiO ₂ , SiO ₂ or activated carbon. For example: US Patent No. 4,264,529 uses a Pt/Al ₂ O ₃ catalyst in the preparation process. Since the carrier of Pt/Al ₂ O ₃ is easily dissolved in an acidic medium condition, the catalyst is seriously lost. Patent CN102658125A uses activated carbon as the carrier, Pt and MoS ₂ as the main catalyst and co-catalyst respectively, and found that when the Pt loading is 2.5-3%, the catalytic activity of Pt/MoS ₂ /C is the highest, and after repeated use, the catalyst Activity remains good. However, the price of Pt is expensive, which will increase the cost of p-aminophenol.

The other type is nickel-based catalysts, such as: Raney nickel (RaneyNi), nano-nickel powder, or TiO2, SiO2 and other substances loaded with nano-nickel. At present, most of Raney Ni is used as a catalyst in industrial production. However, its disadvantages are mainly low activity, poor heat resistance, and poor selectivity, such as hydrogenation on the benzene ring, which is difficult to meet actual needs. Nano-nickel powder has the characteristics of small size, large specific surface area and many surface active sites, and has attracted much attention in the field of catalyst development and application. Du Yan et al. (Journal of Chemical Engineering of Universities and Colleges 2004; 18 (4): 515-518) prepared a nano-nickel powder catalyst with an average particle size of 57nm by means of liquid phase reduction; under the same experimental conditions, the catalytic performance of the catalyst The activity is about 16 times that of RaneyNi commonly used in industry. However, the particle size of this catalyst is small, and there are problems such as not easy to recycle. Patent CN101259414A proposes a new method of loading nano-nickel catalyst on TiO ₂ , SiO ₂ and other substances, using the carrier loaded with quantitative inducer as the precursor to induce hydrazine hydrate to reduce the nickel salt solution, and the loading capacity is 1-50% The nano-nickel catalyst, the size of the nano-spherical nickel particles is in the range of 5-25nm. The preparation method of the catalyst is simple, the nano-nickel formed on the carrier is spherical or quasi-spherical, and its catalytic activity is only equivalent to that of Raney nickel. Therefore, it is of great significance to develop catalysts for the hydrogenation of nitro compounds with high activity, low cost, low pollution and good selectivity.

Contents of the invention

The technical problem to be solved by the present invention is to provide a kind of nano-needle-shaped nickel-coated graphite composite particle and its preparation method and the use of catalytic NaBH4 reducing p-nitrophenol to p-aminophenol for the above-mentioned prior art, and the obtained nano-acicular nickel-coated Graphite composite particles have the characteristics of simple technology, low cost, high catalytic activity, and magnetic properties for easy recycling and reuse. They have broad application prospects in the field of synthesis of p-aminophenol.

The present invention proposes the technical approach that solves the above problem, nano-acicular nickel-coated graphite composite particle, it is the flaky graphite particle of nano-acicular nickel-coated, for adopting the following steps gained product: 1) preparation electroless nickel plating solution; 2 ) After the flake graphite particles are processed, they are placed in the electroless nickel plating solution, after the stirring reaction, suction filtration, washing, and drying obtain nano needle-shaped nickel-coated graphite composite particles, and the electroless nickel plating solution is composed of distilled water, nickel salt, potassium sodium tartrate, sodium hydroxide and 85% hydrazine hydrate, wherein the molar ratio of nickel salt to potassium sodium tartrate is 1 to 6:30, and the molar ratio of nickel salt to sodium hydroxide is 2 to 6:3. The molar ratio of nickel salt to hydrazine hydrate is 1-4:35, and the nickel salt is nickel sulfate or nickel chloride.

According to the above scheme, the weight-to-volume ratio of the treated flake graphite particles to the electroless nickel plating solution is 1-5:1 g/L.

According to the above-mentioned scheme, step 2) stirring reaction temperature is 70～90 ℃.

According to the above scheme, the processing method of flake graphite particles is:

1) cleaning the surface of the flake graphite particles, suction filtering and drying;

2) placing the cleaned flake graphite particles into a nickel sulfate solution to absorb nickel ions, suction filtration, and drying;

3) Reducing the nickel ions on the surface of the above-mentioned flake graphite particles, suction filtering, washing and drying.

The preparation method of the described nano-acicular nickel-coated graphite composite particles comprises the following steps: 1) preparing an electroless nickel plating solution; 2) placing the treated flaky graphite particles into the electroless nickel plating solution, stirring and reacting , suction filtration, washing, and drying to obtain nanoacicular nickel-coated graphite composite particles. The electroless nickel plating solution is composed of distilled water, nickel salt, potassium sodium tartrate, sodium hydroxide and 85% hydrazine hydrate, wherein the nickel salt and The mol ratio of potassium sodium tartrate is 1～6:30, the mol ratio of nickel salt and sodium hydroxide is 2～6:3, the mol ratio of nickel salt and hydrazine hydrate is 1～4:35, and described nickel salt is Nickel sulfate or nickel chloride.

The application of the nano-acicular nickel-coated graphite composite particle as a catalyst for catalyzing the reduction of p-nitrophenol by NaBH4 to synthesize p-aminophenol.

The structure of the composite particles prepared by the present invention is characterized in that the nickel on the surface of the graphite particles is in the shape of nano-needles. The composite particles are low in cost, high in activity, and have the characteristics of being magnetic and easy to recycle and reuse, and can be used to catalyze the synthesis of p _- nitrophenol by reducing NaBH4 p-Aminophenol.

Compared with the prior art, the present invention has the following main advantages:

1. When the nano-acicular nickel-coated graphite composite particles prepared by the present invention are used to catalyze the reduction of p-nitrophenol to synthesize p-aminophenol, this composite particle shows the advantages of the following three aspects: (1) nanometer nickel is loaded on the micron scale Graphite sheets can prevent its agglomeration; (2) Micron-scale graphite is a conductive material that can speed up the transmission of electrons and thus improve the activity of the catalyst; (3) In addition, nano-acicular nickel with a one-dimensional structure can further improve the catalytic performance of composite particles. active;

2. The activity of the catalyst prepared by the present invention is higher, for example: its reaction rate constant (k) for catalyzing the reduction of p-nitrophenol by NaBH ₄ is 8.61×10 ^-2 min ^-1 , which is higher than that of graphite oxide prepared by Ji et al. The k value of ene/nickel nanocomposite (J.Mater.Chem.2012,22,3471) to catalyze this reaction is large (the rate constant is 14.82×10 ^-3 min ^-1 );

3. The nanoacicular nickel-coated graphite composite particles prepared by the present invention have magnetism and are convenient for recycling;

4. The preparation technology of the present invention is simple, low in cost, and convenient for popularization and application.

Description of drawings

Fig. 1 is the SEM figure of commercially available graphite;

Fig. 2 is the XRD spectrum of the nanoacicular nickel-coated graphite composite particles synthesized by Embodiment 1 of the present invention;

Fig. 3 is the SEM figure of the nano-acicular nickel-coated graphite composite particles synthesized by Embodiment 1 of the present invention;

Fig. 4 is the SEM figure of the nano-acicular nickel-coated graphite composite particles synthesized by embodiment 2 of the present invention;

Fig. 5 is the SEM figure of the nano-acicular nickel-coated graphite composite particles synthesized by embodiment 3 of the present invention;

Fig. 6 is the SEM figure of the nano-acicular nickel-coated graphite composite particles synthesized by embodiment 4 of the present invention;

Fig. 7 is the VSM figure of the nano-acicular nickel-coated graphite composite particles synthesized by Embodiment 1 of the present invention;

Fig. 8 is the graph that the nano-acicular nickel-coated graphite composite particle catalyzed by Example 1 of the present invention catalyzes the reduction of p-nitrophenol A-λ over time;

Fig. 9 is the lnA-t curve figure of the nano needle-shaped nickel-coated graphite composite particles synthesized by embodiment 1 of the present invention;

Fig. 10 is a schematic diagram of the synthesis of nanoacicular nickel-coated graphite composite particles synthesized in Example 1 of the present invention.

detailed description

The present invention will be further described below in conjunction with the embodiments and accompanying drawings, but the present invention is not limited.

Example 1

Using 200mL of absolute ethanol as a solvent, add 10g of flake graphite particles into a 250mL Soxhlet extractor to reflux for 8h, filter and vacuum dry for later use. Put the cleaned and dried graphite particles into the nickel sulfate solution for adsorption for 12 hours, filter and dry for later use; then take the above graphite particles and put them in the ethanol solution of sodium borohydride to stand still, and after the graphite particles and the ethanol solution are layered, filter and dry for later use . Prepare another solution by taking 2.63g of nickel sulfate hexahydrate, 25.4g of potassium sodium tartrate tetrahydrate, 0.27g of sodium hydroxide, and 5.2mL of 85% hydrazine hydrate solution to prepare a 100mL solution; put 100mL of the solution into a three-necked flask and heat it to 90 °C, add 0.5 g of pre-treated graphite, and react for 0.5 h. Suction filter, wash twice with deionized water, and dry completely in a vacuum oven to obtain nano-needle nickel-coated graphite composite particles as shown in FIG. 3 .

Compared with the JCPDSNo.08-0415 card of graphite and the JCPDSNo.04-0850 card of nickel, it can be seen from the XRD spectrum in Figure 2 that graphite (002) and Ni (111), (200) and (220) of fcc structure were obtained respectively. ) crystal plane diffraction peaks, and no other heterophase diffraction peaks were found. This shows that the composite particles synthesized in Example 1 are composed of elemental nickel and elemental graphite. It can be seen from Figure 3 that after liquid-phase chemical reduction, the shape of the nickel-coated graphite composite particles prepared in Example 1 is the same as that of the core graphite, and it can be seen from the illustration that the surface of the flake graphite is covered with nano needle-shaped nickel shells. covered by.

FIG. 10 is a schematic diagram of the synthesis of the nanoacicular nickel-coated graphite composite particles synthesized in Example 1. The cleaned graphite particles are negatively charged, and nickel seeds are deposited on the surface of the graphite particles based on electrostatic adsorption, triggering the subsequent electroless nickel plating reaction. Due to the low reaction rate of the system, the growth of nickel nuclei is controlled by the surface free energy, and grows along the <110> direction to grow nano-needle-shaped nickel, and obtain nano-acicular nickel-coated graphite composite particles.

To further illustrate the magnetic properties of the nanoacicular nickel-coated graphite composite particles prepared in Example 1 above, the magnetic properties of the nanoacicular nickel-coated graphite composite particles were measured using PPMS, as shown in Figure 7, and its saturation magnetization is 34.9emu/g. Similarly, the nickel-coated graphite composite particles synthesized in other embodiments also obtain similar results.

In order to further illustrate the catalytic performance of the nanoacicular nickel-coated graphite composite particles prepared in the above-mentioned Example 1 for catalytic reduction of p-nitrophenol to electron transfer reaction. Dissolve 42.5 mg of sodium borohydride solid in 45 ml of deionized aqueous solution, stir evenly, add 5 mg of the above-prepared nano needle-shaped nickel-coated graphite composite particles, and stir at 25°C for 10 min. Then add 5ml of 0.05mM p-nitrophenol and start timing immediately. Samples were taken every 2 min, and the absorbance in the range of 260-500 nm was scanned with a Uv-vis spectrophotometer. As shown in FIG. 8 , it is a graph of the A-λ curve changing with time for the reduction of p-nitrophenol by sodium borohydride catalyzed by nano needle-shaped nickel-coated graphite composite particles. The absorption peak at 400nm is the maximum absorption peak of p-nitrophenol, and the absorption peak at 300nm is derived from its product p-aminophenol. As can be seen from the figure, as the reaction time prolongs, the absorption peak at 400nm gradually decreases, while the absorption peak at 300nm The absorption peak strengthened thereupon, and the solution was nearly colorless after 28 min, indicating that the reaction had been completed. In the experiment of reducing p-nitrophenol with sodium borohydride, the concentration of sodium borohydride is much higher than that of p-nitrophenol, so this reaction can be regarded as a quasi-first-order reaction. According to the first-order reaction kinetics lnA=-kt+c, do The graph of lnA-t is obtained, as shown in Fig. 9, the reaction rate constant of the nanoacicular nickel-coated graphite composite particle catalyst can be calculated to be 0.086min ^-1 . Similarly, the nickel-coated graphite composite particles synthesized in other embodiments also obtain similar results.

Example 2

Using 200mL of absolute ethanol as a solvent, add 10g of flake graphite particles into a 250mL Soxhlet extractor to reflux for 8h, filter and vacuum dry for later use. Put the cleaned and dried graphite particles into the nickel sulfate solution for adsorption for 12 hours, filter and dry for later use; then take the above graphite particles and put them in the ethanol solution of sodium borohydride to stand still, and after the graphite particles and the ethanol solution are layered, filter and dry for later use . Prepare another solution by taking 5.25g of nickel sulfate hexahydrate, 28.2g of potassium sodium tartrate tetrahydrate, 0.4g of sodium hydroxide, and 22mL of 85% hydrazine hydrate solution to prepare a 200mL solution; put 200mL of the solution into a three-necked flask and heat to 80°C , add 0.5g of pre-treated graphite, and react for 0.5h. Suction filter, wash twice with deionized water, and dry completely in a vacuum oven to obtain nano-needle nickel-coated graphite composite particles as shown in FIG. 3 .

It can be seen from FIG. 4 that after liquid-phase chemical reduction, the surface of the graphite particles of the nickel-coated graphite composite particles prepared in Example 2 is covered by nano needle-shaped nickel shells.

Example 3

Using 200mL of absolute ethanol as a solvent, add 10g of flake graphite particles into a 250mL Soxhlet extractor to reflux for 8h, filter and vacuum dry for later use. Put the cleaned and dried graphite particles into the nickel sulfate solution for adsorption for 12 hours, filter and dry for later use; then take the above graphite particles and put them in the ethanol solution of sodium borohydride to stand still, and after the graphite particles and the ethanol solution are layered, filter and dry for later use . Prepare another solution by taking 7.88g of nickel sulfate hexahydrate, 98.5g of potassium sodium tartrate tetrahydrate, 1.8g of sodium hydroxide, and 21mL of 85% hydrazine hydrate solution to prepare a 300mL solution; put 300mL of the solution into a three-necked flask and heat to 70°C , add 0.5g of pre-treated graphite, and react for 0.5h. Suction filtration, washing twice with deionized water, and drying completely in a vacuum drying oven to obtain nano-needle nickel-coated graphite composite particles as shown in FIG. 4 .

It can be seen from FIG. 5 that after the liquid-phase chemical reduction, the surface of the graphite particles of the nickel-coated graphite composite particles prepared in Example 3 is covered by the nano needle-shaped nickel shell.

Example 4

Using 200mL of absolute ethanol as a solvent, add 10g of flake graphite particles into a 250mL Soxhlet extractor to reflux for 8h, filter and vacuum dry for later use. Put the cleaned and dried graphite particles into the nickel sulfate solution for adsorption for 12 hours, filter and dry for later use; then take the above graphite particles and put them in the ethanol solution of sodium borohydride to stand still, and after the graphite particles and the ethanol solution are layered, filter and dry for later use . Prepare another solution by taking 5.94g of nickel chloride hexahydrate, 49.3g of potassium sodium tartrate tetrahydrate, 1g of sodium hydroxide, and 30mL of 85% hydrazine hydrate solution to prepare a 250mL solution; put 250mL of the solution into a three-necked flask and heat to 80°C , add 0.5g of pre-treated graphite, and react for 0.5h. Suction filtration, washing twice with deionized water, and drying completely in a vacuum drying oven to obtain nano-needle nickel-coated graphite composite particles as shown in FIG. 5 .

It can be seen from FIG. 6 that after liquid-phase chemical reduction, the surface of the graphite particles of the nickel-coated graphite composite particles prepared in Example 4 is covered by nano needle-shaped nickel shells.

Example 5

Using 200mL of absolute ethanol as a solvent, add 10g of flake graphite particles into a 250mL Soxhlet extractor to reflux for 8h, filter and vacuum dry for later use. Put the cleaned and dried graphite particles into the nickel sulfate solution for adsorption for 12 hours, filter and dry for later use; then take the above graphite particles and put them in the ethanol solution of sodium borohydride to stand still, and after the graphite particles and the ethanol solution are layered, filter and dry for later use . Prepare another solution by taking 10.5g of nickel sulfate hexahydrate, 225g of potassium sodium tartrate tetrahydrate, 2g of sodium hydroxide, and 80mL of 85% hydrazine hydrate solution to make a 400mL solution; put the 400mL solution into a three-necked flask and heat it to 75°C, add 0.5g of graphite after pretreatment, react for 0.5h. Suction filtration, washing twice with deionized water, and drying completely in a vacuum drying oven to obtain nano-needle-shaped nickel-coated graphite composite particles similar to the previous example.

Example 6

Using 200mL of absolute ethanol as a solvent, add 10g of flake graphite particles into a 250mL Soxhlet extractor to reflux for 8h, filter and vacuum dry for later use. Put the cleaned and dried graphite particles into the nickel sulfate solution for adsorption for 12 hours, filter and dry for later use; then take the above graphite particles and put them in the ethanol solution of sodium borohydride to stand still, and after the graphite particles and the ethanol solution are layered, filter and dry for later use . Prepare another solution by taking 13g of nickel sulfate hexahydrate, 427g of potassium sodium tartrate tetrahydrate, 1.67g of sodium hydroxide, and 50mL of 85% hydrazine hydrate solution to prepare a 500mL solution; put the 500mL solution into a three-necked flask and heat it to 85°C, add 0.5g of graphite after pretreatment, react for 0.5h. Suction filtration, washing twice with deionized water, and drying completely in a vacuum drying oven to obtain nano-needle-shaped nickel-coated graphite composite particles similar to the previous example.

Claims (7)

1. nanometer needle-like nickel bag graphite compound particle, it is the coated flake graphite particle of nickel of nanometer needle-like, for adopting following stepRapid products therefrom: 1) preparation chemical nickel-plating solution; 2) after flake graphite particle is processed, be placed in chemical nickel-plating solution,After stirring reaction, suction filtration, washing, dry, obtain nanometer needle-like nickel bag graphite compound particle, flake graphite particle after treatmentWith the w/v of chemical nickel-plating solution be 1～5:1g/L, described chemical nickel-plating solution is by distilled water, nickel salt, tartaric acidPotassium sodium, NaOH and hydrazine hydrate composition, wherein, the mol ratio of nickel salt and sodium potassium tartrate tetrahydrate is 1～6:30, nickel salt and hydrogen-oxygenThe mol ratio of changing sodium is 2～6:3, and the mol ratio of nickel salt and hydrazine hydrate is 1～4:35, and described nickel salt is nickelous sulfate or nickel chloride.

2. according to the nanometer needle-like nickel bag graphite compound particle described in claim 1, it is characterized in that step 2) stirring reactionTemperature is 70～90 DEG C.

3. according to the nanometer needle-like nickel bag graphite compound particle described in claim 1, it is characterized in that locating of flake graphite particleReason method is:

1) flake graphite particle surface is cleaned to suction filtration, dry;

2) the flake graphite particle after cleaning is inserted to absorbed Ni ion in nickel sulfate solution, suction filtration, dry;

3) reduce the nickel ion of above-mentioned flake graphite particle surface, suction filtration, washing, dry.

4. the preparation method of nanometer needle-like nickel bag graphite compound particle claimed in claim 1, includes following steps: 1) joinChemical nickel-plating solution processed; 2) flake graphite particle after treatment is placed in chemical nickel-plating solution, after stirring reaction, suction filtration,Washing, dry, obtains nanometer needle-like nickel bag graphite compound particle, the weight of flake graphite particle after treatment and chemical nickel-plating solutionAmount volume ratio is 1～5:1g/L, and described chemical nickel-plating solution is by distilled water, nickel salt, sodium potassium tartrate tetrahydrate, NaOH and 85%Hydrazine hydrate composition, wherein, the mol ratio of nickel salt and sodium potassium tartrate tetrahydrate is 1～6:30, the mol ratio of nickel salt and NaOH is 2～6:3, the mol ratio of nickel salt and hydrazine hydrate is 1～4:35, described nickel salt is nickelous sulfate or nickel chloride.

5. according to the nanometer needle-like nickel bag graphite compound particle described in claim 4, it is characterized in that step 2) stirring reactionTemperature is 70～90 DEG C.

6. according to the nanometer needle-like nickel bag graphite compound particle described in claim 4, it is characterized in that locating of flake graphite particleReason method is:

1) flake graphite particle surface is cleaned to suction filtration, dry;

2) the flake graphite particle after cleaning is inserted to absorbed Ni ion in nickel sulfate solution, suction filtration, dry;

3) reduce the nickel ion of above-mentioned flake graphite particle surface, suction filtration, washing, dry.

7. the nanometer needle-like nickel bag graphite compound particle described in claim 1 is as catalyzing N aBH₄Reduction p-nitrophenol is syntheticThe application of the catalyst of para-aminophenol.